Product specifications: 5.1 * 2.2 cm inside casing: 3.0 * 1.4 cm thickness: 0.3 cm Method of use: remove the metal ring, take out the inside of the paper and the writing. Product features: this key card made by new PP material, brightness is good, writing can be made according to the need to identify, easy record and discrimination. Above the label paper is equipped with the plastic protection, metal ring, can replace the pieces of paper on its own. Not suitable for use in the bathroom. including:30pcs